Moisture resistant wrapping material with multiple coatings of vinyl polymer and rubber latex



May 5, 1964 L PIHL 3,132,041

MOISTURE RESISTANT WRARPING MATERIAL WITH MULTIPLE COATINGS OF' VINYL POLYMER AND RUBBER LATEX Filed Jan. 16, 1961 INVENTOR. Z vv/VMT P/HL rrx 'United .StafS Patent y MUIST RESISTANT WRAPPING` MATERIAL WITH MULTWLE CGATENGS F VEWL liLYf i NER ANDRUBBER LATEX w t Lennart Pihl, Solna, Sweden, assigner to AB ,Bonnierforetagem Stockholm, Sweden, a corporation of Sweden l Filed Sian. 16, 1961, Ser. No. 82,8%

Claims priority, application Sweden Nov. 21, 1960 9 Claims., (Cl. 11T-76) v iThe present invention relates to? a vbonding agent of the type which when applied in the form of a layer on` a carriergives goodbonding (cohesion) only on surfaces of vsubstantially the same material as Vthe carrier. but insigniiicant bonding (adhesion) onsurfaces of different material.

"Theinvention also relates to `wrapping material which, on at least one side, is provided with a layer of such a bonding agent. -It 'was previously known that such "a 1ayer',which on account of its above mentioned characteristics is called cohesive; may be made of synthetic or naturalrubber latices, which are modiiiedv by a water "soluble,starchcolloid oricasei'n colloid. Ailayer of these materials is not particularly Water or moisure. resistant. IOf course layers of synthetic or natural rubber-latices are 3,132,041 Patented May 5., 1964 ice vinyl acetate, polyvinyl chloride acetate and the like, an

copolymers thereof. t

Thefcomponent or the components of natural .resin or .articial resin may be added in ther form of an emulsion or dispersion, in which water can constitute thedispersion medium.

Surprisingly a layer of such a material according to the invention when applied to a base material can be com- --pletely water resistant Whileretaining itsrcoh'esive qualities, so that the base material, for example paper with vinyl plastic, for example Saran coated paper, or cellophane can be used for packing vof good containing water. The cohesive properties ofthe layer do not disappear in a water bath; a wrapping of such material according to i l ing); the 'heat required has been so high that it rendered i rto a .certain extent Water resistant'y but this characteristic f is reduced when such arlatex is modified by water soluble '1 vcolloids for the purpose` of adjusting the cohesive prop- Vltihas previously been'pro'posedy hto` produce a moistureV resistant-that isa water vapour resistant*wrapping' mawrapping of temperature sensitive goods, forexarnple ice.- cream and chocolate, diiicult. f t t VFilms made of mixtures .based on, `for example, poly- .vinylidene chloride dispersione and natural rubber latex .have `relatively low water vapour penetration Values of approximatelyy 5,-30 grams/,HL2 per `2,4 hours whenthere -is a 65% diierence in relative humidity at Va temperature of 20 C. Practical vstorage tesis have however shown terial which on one side has a cohesive layer by applying on 'the other side a moisture resistant layer, for example oftvvax, plastic or the like.4 The wax layermcannot ,beV

applied to same side as the cohesive layer owing tothe different physicalproperties ofwax and latexjand it has ynot been possible toobtain sufcient bonding of the coliesive layersfon plastic layers. Wrapping material With suchjllayer's are described for example in UtS. specifications 2,529`,06il and 2,704,732.

Wrapping material of this known kind is not however grams/mf.2 per 24 hours.

that it is desirableto reduce thewater'vapour penetration value even lower, for exampleto a maximum of 1-2 This can be achieved `by the invention, namely by applying a'thin ilm of polyvinylidene chloride aloneunder a filmbased on a mixture of A.plastic dispersion and natural rubber latex; the polyvinyljidene chloride permits very little wateruvapour to peney a water `vapour `penetration value lowerthan lgram/mf particularly cheap to produce and it has also certain disadvantages. The latter'appliesparticularly to ywrapping lmaterial von'which it is desired to print, for example after the wrappingmaterial has beenrmanuiactured (eg. bag) andit gives rise to' diiiiculties on plastic surfaces.

Ari object ofthe invention? is to produce a bonding agent and a 'wrapping material provided with this bonding agent, which in these vrespects isy superior tothe above mentioned'known material Vand in which there is arplastic trate it,

Since the wrapping -rnater'ialgduring its manufacture Ais'forrned i'n several stepsit is possible to obtain per 24 hours. By means of suitable mixing ofthe components inthe various layers itispossible to Obtain complete bondingtof'the various lr'ns `to each otherl so that f :because printing cannot be eiected'on a waxed surface `iilmunderthe cohesive layer.-

Another object ol the ini-"2' vention'` istofrender it possible to modifythe cohesive material irrsuch la way-'thatl a wrapping with 4a layer'of` suchamaterial can also bei-sealed, thatisl closedinsuch a way-'that it cannot be opened without harming the base material. The invention also contemplates such ,a modi- ,ties/are strengthened while its ladhesiveV qualities,'.lthat 'is its` ability .to Vbond ysur'iacesgof. differentv materials. is

weakened y t -l f r[he bondingagent accordingV to the invention is mainly ,i characterized in thatV itV contains oneV or more components y -cation of thecohesivesubstance-that it'scohesivequ'alit consisting-of natural rubber latex or syntheticlatices and f fone or more components kcor'rsisting'of natural resin'or y synthetic resin fromthe 'groupl of vinylpolymers, for exzarnple' polyvinylideneY chloride, polyvinyl chloride,V polyl lfwhenf pressure .sealing is lused Mwrappings are obtained.

Vstrong and wellsealed iz" .By modiiicationvof. the composition of the'bonding V:agent according to the invention it is possible to achieve :an increase'in' the cohesiveproperties of `thesyntheticor natural rubber latex and a reduction in its adhesive qual- A 'ities so that the 4desired selective bonding is obtainedi'o- `gather-,with tl1e bonding to an ,underlyingiplastic layer.

The component or components which. consist of-lnatural rubber .latex or synthetic latices may ofcourse in known vmannerbe modifiedv by a water; soluble colloid; for example ast-arch on` caseinfcolloidfbut thisis 4notnecessaryV since'the component ofznaturalresin or synthetic-resin nfrom the'group of vinyl 'polymers` just'me'iltiored'has` also as .mentioned above the Veffect that theabove-rnentioned synthetic crifnaturalrubber latex/"along or-inv mixture can be given suitable cohesivequalities.Av

An addition' of a plasticizenrsuch 'asesters of a'dipatesfv f phthalatesetc; in anfemulsion-to the naturalruhber latex 1 and plastic dispersion greatly increasesthe cohesive qualitiesof cohesive layer; this eie'cts the strengthjof the C seal` and thespeed atwhich the sealmay belgetlected. .v Whenthe wrappingk material `is' intended for' groceries the In the latter case it is also an ad-V -a .Y selected mixing ratio;

. 3 1 material used must be such as are approved for contact with groceries.

Such latices or plastic products modified by synthetic resins (plastic dispersion) in an aqueous form are normally applied by paper coating machines in which the dispersion is applied to the paper by means of a. smooth roll which extends into the dispersion and transfers an excess of the dispersion onto the paper. The coated paper is moved into the machine and dried either by means of infrared or hot air. It is known to form a plastic film in several steps so that the first applied plastic dispersion dries to form a film and thereafter a new film ties of the layer. According to the invention it is now possible by modification to apply the above mentioned cohesive latices on top of the plastic films. According to thelinvention a polyvinylidene chloride dispersion may vbe'first applied and dried, and then, ina following step,

a mixture of polyvinylidene chloridedisperrsion, and a natural rubber latex containing an antioxidant, dispersion and wetting agent may be applied. In a further third step, if desired, a pure natural rubber latex or mixture of natural rubber latex and polyvinylidene chloride dispersion, for example, may be applied in order to adjust the cohesive qualities. Such a wrapping material produced according to the invention has a very low water vapour penetration value and requires only pressure without heat is applied. In this way it is possible to modify the qualifor sealing. At the same time as a good seal is obtained Manufacture in this manner may, in addition to paper, be effected on laminates of v paper and aluminumfoil or on pure plastic sheets which `adhere to the applied'modified plastic dispersion in aquestep or be moved directly through a multi-stage coating g A machine.

An apparatus for producing wrapping material accord-Y -ing to the invention is described below, together with several embodiments of Wrappings'with reference to the accompanying drawings in which FIGURE l is a diaf grarnmatic representation of a suitableapparatus. FIG.

v2 is a section through one embodiment of Wrapping material and FIG. 3 is another embodiment.`

In the coating apparatus shown in FIG. 1 the base materiaLfor example paper, is rolled from a supply roll .1, moves over guide rollers 2 and then passes in a hori- -of thepaper; The paper then passes in front of a slot-r vshaped mouth piece V5 through which compressed air is .blown onto the paper; this removes surplus coating material-tand .distributes the latter evenly over thepaper.`

The paper is then moved upwardly at an inclined angle Vpast two infra red heaters 6 and is finally rolled up in a dry condition in a roller 7.. `This apparatus can also be so constructed that` the coating is effected in several steps; after the `first drying devices there are one or vmore coat v ing members with succeeding drying devices.

- The, wrapping` material shown `in section inY v,2

consists of a base material 8, for example paper, on which n there is a'thin layer 9` of polyvinylidene chloride and on vtop of the latter a further thin layer 10 consisting of a mixture of polyvinylidene chloride and natural rubber latex. Thewrapping material shown in FIG. 3 consists .of a base material 11,2for example paper, a thin layer 12 consisting'of polyvinylidene chloride anda thin layer 'mixture-.of- 80% .ber latex and 20% by volume of 50% of a water dis- 13 consisting of a mixture of equal parts of polyvinylidene chloride and natural rubber latex, and thin top layer 14 of a mixture of 5% of polyvinylidene chloride and 95% natural rubber latex.

Several examples of wrapping material according to the invention are given below.

Exaniple 1 A 60 grams/m.2 bleached smooth kraft paper is coated in a coating apparatus with a plastic dispersion in the following manner. The-paper Iis moved over the coating unit in which 5-25 grams/m.2 of a 50% water dispersion of polyvinylidene chloride, for example the type Diofan 230 from BASF, is applied; the dispersion is then dried by infra red device. After the dispersion has dried, 5-8 grams/m.2 of a mixture of equal parts of a 50% aqueous dispersion Aof polyvinylidene chloride and '60% natural rubber latex containing smaller` quantities (1% of liquid weight) of sodium alkyl sulphonate as a dispersion and wetting agent. After the application the Vlayer is dried, and a third coating of 5-8 grams/m.2 of a mixture of parts.60% natural rubber latex and 20 parts 50% aqueous dispersion of polyvinylidene chloride containing the above mentioned wetting agents is applied. A further layer can be applied in a'fourth step if it is desired for example, toincreasethe strength of the bond; this layer is a thin coating of naturalv rubber latex stabilized by casein and containingfanti-oxidant, for example butyl hydroxyltoluol (BHT) in a quantity` of 2 percent by weight of the natural krubber latex. The application in the fourth step can-be effected in the s ame manner as in the previous three steps.` The papercan be rolled .up without any jamming or adhesion in the roll, and the applied layer has good Water moisture sealingrproperties and can only adhere to itself (cohesive bond).

Example 2 45 V,95% of :160% natural rubber latex mixed with 10%- 20% BHT emulsion and 5% of a 50% aqueous dispersion of polyvinylidene chloride is applied. In this Way a coated paper with smaller total quantity of plastic is obtained.

Y Example 3 A mixturel of 65% by volume'of a 60% natural rubber latex and 35% by livolurne of a 40% aqueous dispersion-ofv polyvinylidene chloride is prepared and is appliedfin a lqllantity of5-25 grams/m.2 in liquid form to a paper base material. After the applied layer has dried it hasv cohesive qualities (selective adhesion) and Iis also moisture resistant. A wrapping material of this lkind can advantageously be fused for wrapping certain groceries, cigarettes -and other moisture sensitive articles etc. i

'Ilhe bondingfagent produced according to ythe example (applied on one side of the sutlphite-paper in a quantity of 40 grams/m2 has a water vapour penetration ofY 5 grams/m2 per 24Vv hours When there vis a difference in relative humidityl of 45% in the air on both sides of .the paper. YThis figure rneetsthe requirements of water vapour resistance fora Wrapping Vmaterial for e.g.

cigarettes or -the like.r Example ,4

by volume of 60% natural rubpersion of polyvinylidene chloride is prepared and is applied in la quantityof5-25 grams/:n.2 on the base material. After drying thev applied vlayer has cohesive according to the following:

qualities.. :'The' cohesive .brindis however, in c'ntr-a distinction to the casein Example )3, above irreversible, that is a wrapping of this material is sealed in such a way that it cannot again be open without destroying the base material, which in somecases may be desirable for ex- `ample for certain unitpackages (spices, tea and the like). i Depending on the type of latex plastic dispersionmixture which is used it is possible tofobtain "a bond by "means of the ibonding agent according to the invention which is either reversible or irreversible; this is achieved in the former case by using a larger and in the latter case byusing a smaller addition of natural or synthetic resin. i

The wrapping material 4according to the invention can also be used to protect goods, for example groceries, against biological damage by organisms ofthe type thallus, for example bacteria, fungi and theV like. For this purpose according tothe invention fungicidal or bactericidal carbonate. Y l

The proportions usedV are given in the following example:

Percent by volume Latex 50 Casein solution 2O Glycerine 10 Cyclohexyl amine carbonate solution 20 substances are added to the bonding agent or to the base material or to both. Examples of fungicidal substances are paraoxy-benzoic acid. Para-nitro-benzoic acid and/ or esters of these, dihydro acetic acid, diphenyl, ortho phenyl phenol and terpineol which can Abe used individually or ina combination with each other. Examples of bactericidal substances are paranitrobenzoic acid terramycin, amomycin, penicillin, and/or their esters,

antibiotics of the streptomycin type and/or their esters. which may be used individually or in combination with each other. An example of the wrapping material with' the fungicidal action'is given below.

` v Example 5 A paper made of bleached sulphate pulp having a Weight of 40 grams/m.2 is used as a base material, and it is coated with a quantity of 5-25 grams/m2. The -first layer consists of -a mixture of equal'part of la 50% aqueous dispersion of polyvinylidene chloride and a 60% naturalrubber latex contain-ing 2% sodium alkyl sul- Aphonate as wetting agent. A bonding agent is introduced into a second layer which comprises a 25 ammonia stabilized natural rubber latex to which has been added 5 percent :solution of`a carboxy methylcellulose solu-V tion and glycerine and lan aqueous emulsion of diphenyl Percent by volume Latex 65 Carboxymethylcellulose 20 Glycerine Diphenyl emulsion v 5 Contraryrto what would have been expected the bonding agent does not prevent the action of the fungicidal a'que'ous 'dispersion of pol natural rubber latex containing`2% Isodium alkyl sulphonate as wetting agent. A `second Elayer of a self adhesive bonding agent containing 60% ,ammonia stabilized natural-rubber 'latex containing a 20%, casein solution and glycerin is applied. the self-'adhesive layer a corrosion inhibitingsubst-ance is included; in this case lit comprises `a`5 0% aqueous ysolution of cyclohexyl amino This packing material, which iis self-sealing can be used, for example as wrapping paper or for manufacture of bags or every'type of wrapping. As a result of the bonding agents low vapour penetrability with respect to the vapour of the inhibitor and owing to the fact that the wrapping can effectively be closed by means of the bonding agent an adequate erosion protection is obtained for the packed material.

VIt is also possible to add sodium benzoate in an aqueous solutionand if desired sodium nitrite to the selfadhesive coating; these compounds also prevent corrosion of metals by contact action. f

What is claimed is: e `1. Moisture resistant 'cohesive coated paper Wrapping material comprising a thin sheet of base material having on one side thereof a base layer of a rst coating material .Y yconsisting of aY water insoluble vinyl polymer and a secagent, which therefore acts on the contents of the'Wrapping-to protectrit from fungicidal attack. n

It is also possible by means of the Wrappin'grmaterial,

according to lthe invention to protect metals against corrosion,` for example iron and steel from rust, by .includinga corrosion preventing or corrosion reducing 'agent-inthebasematerial and/or Ithe bonding agent.

Such chemical inhibitors operate, for'example, in such vapour phase, which in Ithis-way inhibits corrosion. Certain organic nitrites, ttor example d-icyclobexylamine lnit-rite, iare examples o f such-substances which are known y under the name VPI (vapour phase inhibitors). VAn even more eective compound is cyclohexyl amino carbonate. i `An example of a wrapping material according to the invention suitable for Wrapping of iron products, steel or fj the like is Athe lfollowing. 1 Y y Example Y 6 away that they surround the ywrapped material with their v f protecting a product against corrosion, wherein at least one of said layers ofv coating material has incorporatedf i A base material which comprises a7 paper -made VfromV bleached kraft pulp having a weight ot 5,0 grams/mais f coated with a iirst layer inaqu-antity 'of'S-ZS grams/m The layer consists ofa mixture of equal `parts of a 50% -plasticizer selected from the ond layer of a second coating material consisting of'a water insoluble vinyl polymer and a rubber latex selected from the group consisting of natural and synthetic rubl ber latices, said vinyl polymer and said .rubber latex be- Y ing presentl inthe proportions of between equal parts of va 50% aqueous dispersion of vinyl polymer and v60% Y of natural rubber latex to 5% vinyl polymer and 95% natural rubber latex.

2. A wrapping material in accordance With claim 1,l

5. A wrapping material yin accordance with claim 1, vcomprising further a layer o f a third coating material consisting of a casein-stabilized rubber latex wherein said latex is selected from-the group consisting of natp ural and synthetic rubber latices. v v

, 6. A wrapping material in accordance with claim 1 for protecting a `product against harmful organisms,

wherein at least one of said layers vhas incorporated p therein a substance which renders said organisms harmless.

7. A wrapping'material in accordance with claim llfor therein a corrosion-inhibiting` substance.

8. A moisture resistant cohesive coated paper wrapping:

- material comprising a4 basesheet of Vpaper havingon at least vone side` thereof a layer of a rst coating material l consisting of a dispersion of AWater insoluble polyvinyliyvi-nyflidene` chloride |-and 60% polyvinyl acetate and copolymers of polyvinylidene chloride.

References Cited'inthe iile of this patent UNITED STATES PATENTS Shoan 1 Aug. 4,` 1942 Trillich Nov. 7, 195() copeman et al. 1 Mar, 22, 1955 Herzfogetjal. 'May 31, 1.9575

Lcyet :11.vk May 8, 1962 

1. MOISTURE RESISTANT COHESIVE COATED PAPER WRAPPING MATERIAL COMPRISING A THIN SHEET OF BASE MATERIAL HAVING ON ONE SIDE THEREOF A BASE LAYER OF A FIRST COATING MATERIAL CONSISTING OF A WATER INSOLUBLE VINYL POLYMER AND A SECOND LAYER OF A SECOND COATING MATERIAL CONSISTING OF A WATER INSOLUBLE VINYL POLYMER AND A RUBBER LATEX SELECTED FROM THE GROUP CONSISTING OF NATURAL AND SYNTHETIC RUBBER LATICES, SAID VINYL POLYMER AND SAID RUBBER LATEX BEING PRESENT IN THE PROPORTIONS OF BETWEEN EQUAL PARTS OF A 50% AQUEOUS DISPERSION OF VINYL POLYMER AND 60% OF NATURAL RUBBER LATEX TO 5% VINYL POLYMER AND 95% NATURAL RUBBER LATEX. 